Aren’t kids amazing? Social distancing, lockdown and home-educated all 2020 and they still manage to get Headlice.
I wrote a few parenting books in the Nineties and the only bit I’m really proud of was my thoroughly researched chapter on threadworms and headlice.
The rinse on and off shampoos have done more harm than good because they’ve encouraged resistance in the lice.
The only lotion that worked for us was Derbac but I think it’s either off the market or restricted because it’s a nerve agent or something (you can probably get it in Russia in that case)
Just what @sirChenjin said. Very wet hair well anointed with conditioner. This immobilises the adult lice.
Comb each small section root to tip once only between thorough rinsing of the comb under the tap. Use a proper nitcomb. Best done with kid seated, wrapped warmly, by bathroom basin.
Repeat as advised or every 3-4 days over 15 days, covering a life cycle. Brush kids hair a lot to monitor - also this may help injure new adults.
Don’t bother trying to comb out with dry hair - the lice are too quick.
The “nits” are empty eggs, the only point in removing them is because they are unsightly. Live eggs are laid right at the root of a hair where the human body warmth incubates them and they’re pretty well invisible.
And keep up a regular combing out routine if the kids are in a situation where they might get them.
Good luck.